In many cases, PTP (press through package) for packaging medicine is structured by combining a container and a cover. The container need be formed by deep drawing, and the container of an ordinary strip package body utilizes a plastic film such as a resin film of polypropylene and the like. In particular, regarding a tablet and the like which require a vapor barrier property during storage, a composite body having an aluminum alloy foil with high barrier property and a resin film bonded on one side or both sides thereof is often used. In recent years, medicines take various shapes and sizes, and thus the package for packaging these medicines need be formed with a deeper shape for complying with such shape.
In addition, in order to provide vapor barrier property to an external material of a secondary battery, a material structured as a composite body having resin films bonded onto both sides of an aluminum alloy foil is used. In recent years, reduction in size and weight have been seen in electronic devices such as a mobile communication device, a laptop computer, a stereo headphone, a camcorder and the like. Accordingly, secondary batteries such as a lithium ion secondary battery and the like having a thin sheet form are appreciated as a driving source of such devices. Charging capacity or high output capable of enduring the long-term usage is required for the secondary battery. Therefore, the structure of the battery element structured with and electrode and a separator has become complicated and multilayered. This resulted in the requirement to bulge of deeper concave portions and the like under severe conditions.
In particular, regarding the external material of the lithium ion secondary battery having a thin sheet form, square-cup drawing is conducted. In the square-cup drawing, the radius R of the shoulder portion and the corner portion are made smaller at the four corners of the bulged concave portions. Accordingly, the bulging height can be made deeper, thereby resulting in increase in the amount of the electrode material filled in the bulged concave portions and achieving higher battery capacity. In addition, when a square-cup drawing test is conducted, high blank holding force is often applied in order to suppress the occurrence of flange wrinkles. When a high blank holding force is applied, a high friction force is generated in between the both surfaces of the die and the external material, resulting in heavy punching load. Accordingly, in order to conduct a deeper bulging in the square-cup drawing, it is important to improve the strength of the external material of the lithium ion secondary battery. That is, high strength is required for the aluminum alloy foil structuring the external material of the lithium ion secondary battery.
As shown in FIG. 2, the package body 1 for forming is generally structured by laminating a heat sealing layer 9 on one side of the external material main body 8, and a synthetic resin film 10 on the other side thereof. As shown in FIG. 1, the package body 1 is bulged so as to have a concave portion in the center portion and a planar portion in the peripheral portion. The concave portion is provided to contain the laminated body such as the positive electrode current collector 2 and the like. Therefore, it is necessary to use the external material main body 8, the heat sealing layer 9, and the synthetic resin film 10 having superior formability.
Conventionally, as the external material main body 8, metal foils with low moisture and air permeability and superior formability, especially an aluminum alloy foil has been preferably used, in order to avoid adverse effect on the quality of the content. As such aluminum alloy foil, the ones with the composition specified by JIS 1100, 3003, 8079 or 8021 has been mainly used.
For example, regarding the external material main body 8, an aluminum foil having a thickness of 20 to 60 μm, and being elongated by 11% or more, the elongation being in the direction of 0 degrees, 45 degrees, and 90 degrees with respect to the rolling direction, has been suggested (Patent Literature 1). In addition, also regarding the external material main body 8, an aluminum alloy foil having a superior corrosion resistance, containing 0.8 to 2.0% of Fe, 0.02 to 0.05% of Cu, and 0.03 to 0.1% of Si has been suggested (Patent Literature 2). In addition, also regarding the external material main body 8, a high-strength aluminum alloy foil containing 0.8 to 2.0% of Fe, 0.2% or less of Si, and 0.1% or less of Mn, with specified intermetallic compound having a circle equivalent diameter of 0.2 to 1.0 μm (Patent Literature 3).